Pressurized afterburner cooling shroud



Aug. 12, 1958 n.1. JORDAN PREssURIzEn AFTERBURNER COOLING sHRoUn Filed Oct. 25, 1952 vN EN IIL Nu wf' N /lvvENro/e .DONALD J. JoRoA/v United States Patent O PRESSURIZED AFTERBURNER COOLING SHROUD Donald J. Jordan, Glastonbury, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application october 2s, v1952, serial No. 316,905

z claims. (ci. so-35.6)

This invention relates to improvements in a pressurizing system for a duct and has particular reference to a pressurized shroud which, while not limited thereto, is particularly adapted to an afterburner of `a jet engine.

An object of this invention is to pressurize a space around the afterburner when the afterburner is in operation.

Another object of this invention is to provide an afterburner cooling system which will permit an afterburner of a jet engine to operate at a high temperature and sustain high internal pressures.

A further object of this invention is toprovide a cooling system whereby air is accelerated to a high velocity in. a shroud at the aft end of an afterburner, thus providing ecient cooling ofthe skin of the afterburner.

Another object is to provide a cooling system which will permit the inner skin ofthe afterburner to be uniform in cross sectional thickness and to have no discontinuities.

Other objects and advantages will become apparent from the following description.v

In the accompanying drawings there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention. The drawings, however, are for the purpose of illustration only and are not to be taken as limiting or restrictingk the invention. It will be apparent to` those skilled yin the art that various changes in the illustrated. construction may be made without exceeding the scope of the invention.

Fig. l is a view inelevationof ajet engine and afterburner showing part of the cooling system.

Fig, 2 is an enlarged view of a section of the afterburner partially in cross section showing. the. construction of the pressurized cooling shroud.

Fig.. 3 is an enlarged cross sectional View of the pressurized cooling shroud showing the forward support, the rearward. support and the connection of the compressed air. pipes with` the shroud- Fig.. lA shows a jet engine2 having. an' air inlet 4, a. compressor section 6, burner section. 8, turbinesection 10, and having an afterburner 12 and nozzle 14 attached thereto. The nozzle shown in these lgures. is shown andV claimed` in U. S. Patent No. v2,831,319.. While a particular nozzle has been shown in these figures, it is to be understood that any type nozzle desired may be used'.

The afterburner 12 includes' a diffuser' section 16 and a burner section 18'. These two sections, 1'6` andV 18, are attachedI by means of `a flange 20 on the diffuser section 16 and a ange 22 ony the burner section18i These flanges are held together by bolts 24. The nozzle 14`v is attached to the Vafterburner 12 and is actuated yby pistons in*V cylinders 26. An actuating iluidl is directed to said' cylinders in a manner to beA hereinafter described. K

As seen inr Figs` 2 .and 3 the burner section 18 of the atterburner is constructed having twoVV shells, an inner shell 28 andl an outer shell, or shroud, 30. The outer 2,846,841 Patented Aug. 12, 1958 ICC shell 30 is connected at its forward end to the diffuser sectiony 16 of the afterburner by flanges 20 and 22 as herein described before. The forward end of the inner shell 28 is allowed to iloat between the forward end of the outer shell and a ilat annular ring 32 which is secured in place by an integral flange 34 which is held between the flanges 20 and 22. This forward mounting arrangement permits the inner shell to expand both longitudinally and radially. The rearward ends of the inner and outer shells are connected by a plurality of mounting devices 36. These devices permit relative radial movement between the two shells, 28 and 30.

These devices include two units. One unit is fixed in relation to the inner shell and the other unit is xedin relation to the outer shell. The unit fixed to the outer shell consists of a spacer 38 and bushing 40v which has a circular flange 42 attached thereto. The bushing fits into a hole 41 in the outer shell and the spacer 38 and iiange 42 are attached to the outer shell around said hole by any means desired. The unit xed to the inner shell includes a bolt 44 which extends through a hole 46 in said inner shell and has a head tapered at 48 to iit in a tapered part S0 of the hole 46. A sleeve 52 is placed with its inner diameter around said bolt and with its outer diameter engaging the inner diameter of bearing 40 in a manner to permit sliding motion therebetween, the length of the sleeve 52 being longer than that of the bearing 40. A washer 54 is placed over the thread. ed free end of the bolt 44 against the end of sleeve 52. A nut 56 is-k then placed on the threaded free end of the bolt 44 and positioned so as to fxedly mount this unit to the inner shell 28. As it can now be seen, rela-V tive radial' movementis permittedbetween the inner shell and the outer shell, or shroud 30 by an amount equal tothe dilerence in length between the sleeve 52 and the bearing 40.

Compressed a'ir is introduced into the area between the inner shell 28 and outer shell, or shroud, 30 through a piping system 58'. This system as shown includes a pipe 60 connected' to the compressor of the engine in such a manner that compressed `air caribe fed into it, a presysure valveA 62 for controlling the admission of the compressed air which operates in a manner to be later herein described, and a Y section of pipe which permits a header 66 to extend down on either side of the engine (only one side being shown in Fig. 1). Each header has three' connections 68 which are connected by pipes 70 to pipe sections 72 which are in turn connected to the outer shell, or shroud, 30 by `a flared out section. These sectionsare ilared to insure a smooth flow of air into the area to be pressurized and also to insure that the pres-i surized air willv be introduced through a greater degree of are to assist in circumferential distribution of the pressure. Sufficient pressure is introduced into the area between the shells at 74 so that the combustible gas at 76v will not flow through the forward mounting arrangement of the inner shell 28. While the supply of compressed air is shown as the compressor of the engine, itis to be understood that the air may be supplied from any means desired. It is also to be understood that other types of cooling uids besides air may be used.

Downstream from the points at which the air is introduced into the area between the inner and outer shells a circumferential restriction 78 is placed to further aid in equalizing the pressure of the air around the entire circumference Iof the volume between the inner and louter shells 28 and 30. This restriction is formed by a rigid circumferential member 80, a ilexible circumferential seal member 82 fand a plurality of spacers 854".

, These three parts of the restriction .are fixed to the outer shell' byI a plurality of bolts' 86 spaced therearound.

The rigid circumferential member 80 is formed having a flat circular part 88 and a frustro-conic'al part 90. The free edge of the frustro-conical part of this member 80 is spaced from the inner shell 28. This spacing permits eXpansion of the inner shell in relation to the member. To restrict the annular opening 81 formed between the member 80 and the inner shell 28 a flexible circumferential seal member is used. This seal member 82 is formed from two members each having a at circular part 92 and a frustro-conical part 94. The frustro-conical portion of each member is segmented and the segments of one frustro-conical section cover the meeting edges of the segments of the other frustro-conical section. This arrangement provides a leaf spring action which restricts the annular opening 81 formed between the member 80 and the inner shell 28 as the inner shell and outer shell move in relation to one another. Each bolt 86 referred to above extends from the outer shell through a spacer 84, a hole in the flat annular part 92 of the seal member 82 and a hole in the at annular part 88 of the rigid member 80. The height of the spacer 84 determines the size of the restricted opening.

From the restriction 78 to the end of shell, or shroud, 30 the annular space between the inner shell 28 and outer shell, or shroud, 30 is gradually decreased. At the end of the outer shell, or shroud, 30, a ring 96 and a flexible circumferential seal member 98 are mounted. Ring 96 is mounted to the outer shell, or shroud, 30 by means of a flange 100 on said outer shell and a flange 102 on said ring. Bolts 104 secure one tlange to the other. The free end of ring 96 has a frustro-conical section 106 with a flared portion 108. This flared portion 108 is spaced from the free end of the inner shell 28. The dimension of this space is such that when the nozzle 14 is Open and the afterburner is on the free end of the inner shell will be approximately just in meeting contact with it. A ring of this type is shown and claimed in U. S. Patent No. 2,735,262. Holes 110 are provided in the frustro-conical section 106 of ring 96 .to permit the air to flow through said outer shell, or shround, 30.

Seal member 98 is also mounted on the outer shell 30. A flange 112 on said member is secured to flange 100 by bolts 104. The free end of said seal member contacts a member 117 of the nozzle 14 to prevent a leak at this point when the nozzle is in a closed position.

Itis desired to have air owing through the piping system 58 and between the inner and outer shells 28 and 30 when the afterburner is on and the nozzle 14 is openf Conversely, it is desired that no air be flowing through the piping system 58 and between .the inner and outer shells 28 and 30 when the afterburner is oi and the nozzle 14 is closed since at this operating condition there is no need for this action.

While the above operation can be performed manually by having a manually controlled valve in place of pressure valve 62 and making nozzle 14 a manually operable nozzle, it is preferred that an automatic control be used. An automatic control of a type which could be used is shown and claimed in U. S. Patent No. 2,715,311. This control senses when the afterburner goes on or off, and opens or closes the nozzle accordingly and maintains it in that position. When the afterburner is on this nozzle and valve -actuator control 115 permits an actuating fluid to be directed by conduit 262 to manifold 116 and in turn delivered to the rearward ends of cylinders 26 by conduit sections 118. This connection holds nozzle 14 open When the afterburner is olf this nozzle and valve actuator control 115 permits an actuating fluid to be directed by conduit 266 to manifold 120 and in turn delivered to the forward ends of cylinders 26 by conduit sections 122. This connection holds nozzle 14 closed Pressure valve 62, which regulates the admission of compressed air to the space between the inner and outer shells may be of several types depending on how it is connected to the nozzle and shroud actuator control.

One type is a pressure valve which is normally closed and arranged to open when subjected to a predetermined pressure. This valve can then be connected to conduit 262 by conduit 124 and the proper operation of both the cooling system and nozzle would be obtained. A second type is a pressure valve which is normally open and arranged to close when subjected to a predetermined pressure. This valve can then be connected to conduit 266 by a conduit and the proper operation of both the cooling system and nozzle would be obtained. A third type is a pressure valve which has two pressure actuated members, one arranged to open said valve when subjected to a predetermined pressure and the second arranged to close said valve when subjected to a predetermined pressure. The member of the valve which opens said valve can then be connected to conduit 262 by conduit 124 and the second member of `the valve which closes said valve can then be connected to conduit 266 by a conduit and the proper operation of both the cooling system and nozzle would be obtained. This last type of pressure valve provides for positive actuation in both the opening and closing directions.

When the afterburner is turned on, the nozzle and valve actuator control connects conduit 262 to an actuating uid and connects conduit 266 to drain. This actuates pressure valve 62 through conduit 124 in an opening direction and nozzle 14 through manifold 116 and conduits 118 in an open direction. When the afterburner is turned off, the nozzle and valve actuator control 115 connects conduit 266 to an actuating fluid and connects conduit 262 to drain. This actuates pressure valve 62 in a closing direction and nozzle 14 through manifold 120 and conduit 122 in a closing direction.

Although a specific pressurizing system has been shown and described herein for purpose of illustration, it Will be evident to those skilled in the art that the invention is capable of various modifications and adaptations within the scope of the appended claims. The specific mounting arrangement of a pressurized shroud as shown in this application is shown and claimed in application Serial No. 316,920, filed October 25, 1952, to Edmund D. Brown for an Afterburner Shroud Construction.

I claim:

1. A jet engine having in combination, a compressor, a turbine, an afterburner downstream of said turbine, said afterburner having two shells, and means for pressurizing the space between said shells with a cooling fluid and permitting said fluid to flow therethrough, means in the space between said inner and outer shells for restricting the ow of cooling fluid through said space, said last named means including an annular flexible member and a rigid annular member, the outer edge of said annular members being Xed to said outer shell with a plurality of spacers located between the members and said outer shell, the inner edge of said flexible member being biased against the inner shell while the inner edge of the rigid member is spaced from the inner shell to permit expansion of the inner shell in relation to the rigid member.

2. A jet engine having in combination, a compressor, a turbine, an afterburner downstream of said turbine, said afterburner having two shells, said two shells forming a space therebetween, and means for pressurizing the space between said shells with a cooling fluid and permitting said uid to ow therethrough, said last named means including openings into the forward part of the space, means in the space between said inner and outer shell adjacent said openings for restricting the flow of cooling fluid through said space, said last named means including two juxtapositioned annular seal members each having a cylindrical portion and a segmented frusto-conical portion projecting inwardly therefrom and each having its cylindrical portion xedly spaced from said outer shell with the segments of said frusto-conical portion of one of said seal members overlapping the segments of said References Cited in the le of this patent 5 UNITED STATES PATENTS Redding May 23, 1950 Alford et al. May 1, 1951 Meyer June 3, 1952 10 6 Brown July 15, 1952 Mierley Nov. 4, 1952 Crook Jan. 13, 1953 Mierley et al. Ian. 20, 1953 Woll Mar. 10, 1953 Williamson et al Mar. 17, 1953 Pouchot May 26, 1953 Hoffman Sept. 15, 1953 Coar Aug. 16, 1955 

